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Eogranivora: an Early Cretaceous chicken!

Updated February 5, 2018 with higher resolution data of the skull. Not much changed. Eogranivora is still a chicken sister.

This was predictedby the large reptile tree (LRT, 1054 taxa, subset Fig. 3) and overlooked by the original authors due to a lack of an accurate tracing of the skull. Extant birds had their origin in the Early Cretaceous… they just have not been discovered there, until now.

Figure 1. Eogranivora from Zheng et al. 2018 with DGS colors added and reconstructed. Except for the longer wings and straight rostrum, most traits found here are also found in Gallus the chicken (figure 2).

Figure 1c. Skull of Eogranivora in situ and reconstructed using DGS, replacing a lower resolution attempt. Some details added for the palate here. It’s still a chicken sister.

Eogranivora edentulata (Zheng et al. 2018; Early Cretaceous, Yixian Fm. Aptian, 125 mya; STM35-3) was earlier referred to Hongshanornis by (Zheng et al. 2011) who found evidence for an avian crop, along with feathers, gastroliths and seeds in the present specimen. Distinct from the holotype of Hongshanornis, Eogranivora is toothless.

Figure 2. Gallus, the chicken, nests as a sister to the Early Cretaceous, Eogranivora, also a seed-eater.

The authorsincludedGallus the chicken (Fig. 2) in their taxon list, but failed to nest the two taxa together… even after noting that Eogranivora was a seed eater. So, this one cannot be attributed to taxon exclusion, but taking a look at their tracing of the specimen (Fig. 1) indicates they put little to no effort into deciphering the crushed bones of this complete and articulated specimen. They could have used a little DGS, which always comes with a reconstruction (Fig. 1 skull, pes).

With larger wings and a smaller bodyEogranivora would have been a better flyer than extant chickens. And that’s to be expected.

Figure 3. Eogranivora nests with Gallus the chicken in the LRT, confirming the origin of Ornithuromorpha in the Early Cretaceous, which makes it that much easier to have highly derived penguins appear in the Paleocene.

You may rememberthe highly derived penguins first appear in the Paleocene. The appearance of volant chickens in the Early Cretaceous makes this easier (more gradual), and falsifies the earlier widely-held hypothesis of a fast radiation of extant birds shortly after the K-T extinction event.

This could have been a big news event.
Unfortunately, it falls to bloggers to make the importance of this fossil widely known.

3 thoughts on “Eogranivora: an Early Cretaceous chicken!”

The bone identifications in the skull are basically all illusions caused by the low res photo you used. If you look at Zheng et al.’s figure 3a, your jugal and anteroventral sclerotic plates are just cracks. Similarly, that ‘gap’ below your jugal is full of bone, and the whole area inside your sclerotic ring is the ventral surface of the frontal. Your hand interpretation gets more right, but check out their figure 4a to see phalanges II-1 and III-1 aren’t fused, that there’s a small III-2, that there are only three phalanges including the ungual in digit II (your II-2 and II-3 are just II-2). Or there’s the fact your right scapula doesn’t exist and the actual scapula is what you show as the anteriormost long sternal process, but in the high res figure S1 you can see the real scapula’s bulge extend under the sediment to ahead of the sternum. And I could go on, but so many errors like these help place Eogranivora by Gallus (which is also interpreted wrongly- e.g. no living birds have postfrontals, not even embryologically). It shouldn’t be surprising given its age.

Higher resolution of the skull (see above) still nests this taxon with Gallus the chicken, postfrontals and all. The scapula you note appears to be ventral to the ribs, despite the bulge, which is provocative, yet duplicated on the opposite side. Since chickens have giant scapulae, this remains an interesting possibility.